Battle of Keos (431 BC)

The Battle of Keos was a naval battle fought off the coast of Keos in the Cyclades archipelago in 431 BC during the Peloponnesian War. The battle saw the Athenian navy under Stelios the Cloaked defeat the defending Spartan fleet of Maleos the Sea-Legged and conquer the Pirate Islands for the Delian League.

Background
In 431 BC, the pirate admiral Xenia and her fleet took control of most of the island of Keos from Sparta, burning Koressia to the ground and mandating that all people over the age of 60 had to drink hemlock poison, thereby offsetting the effects of a horrific food shortage. The pirates failed to conquer the whole of the island, as the Peloponnesian League ally Dexios the Envious remained in power at the Koressia Fort. However, Xenia sent the mercenary Kassandra to loot the fort's nation chest as a means of paying her for information on the whereabouts of her mother, Myrrine, and Kassandra assassinated Maleos, killed the fort's garrison, slew several mercenaries, looted the fort's treasures, and burnt the Spartan war supplies in the process. This weakened Sparta enough that Stelios the Cloaked and an Athenian force landed at Poiessa Village, setting up a base camp. Stelios hired Kassandra to join the Athenian fleet for the battle, and she contributed her trireme Adrestia.

Battle
The Athenian fleet met the Spartan fleet in a nighttime naval battle off Keos, with the island's pirate ships disrupting the battle by attacking both sides. Kassandra attacked several pirate vessels and salvaged their materials to repair the Adrestia, providing the Athenians with a strong flagship. The Adrestia succeeded in sinking several Spartan vessels either through boarding actions or through ramming them and cleaving them in half, and all four Spartan ships and a few pirate ships were destroyed. With the Spartan defensive fleet destroyed, the Athenians occupied the Pirate Islands without resistance, a major victory for the Athenians in the Aegean Sea.